1. Field of the Invention:
This invention relates to an air conditioning apparatus, in which a passage in an air conditioning case is partitioned into a first air passage at a side of an inside air and a second air passage at a side of an outside air. A high-temperature inside air having been heated re-circulates and is blown out from a foot air outlet, and an outside air having a low-humidity is blown out from a defroster air outlet, to improve a heating capacity and to defrost a windshield.
2. Description of Related Art:
In a conventional air conditioning apparatus as disclosed in JP-A-5-124426, there are formed at one end side of an air conditioning case an inside-air inlet for introducing inside air and an outside-air inlet for introducing outside air and at the other end side of the air conditioning case a foot air outlet for blowing air toward a foot area, a defroster air outlet for blowing air toward an inner surface of a windshield, and a face air outlet for blowing air toward a face area.
In the air conditioning case, there is provided a partition plate for partitioning an interior of the air conditioning case into a first air passage extending from the outside-air suction port to the face air outlet and the foot air outlet and a second air passage extending from the outside-air suction port to the defroster air outlet.
Further, in each of the first and the second air passages, there are provided a heating heat exchanger, a bypass passage bypassing the heating heat exchanger, and an air mixing door. The air mixing door includes a door at a side of the first air passage, and another door at a side of the second air passage, which are integrally provided with a single rotary shaft rotatably disposed over both air passages.
When any one of the face mode, the bi-level mode, and the foot mode is selected as air outlet mode, if the inside air/outside air introduction mode is set to the inside-air circulation mode, the inside air is introduced into both air passages, whereas if the mode is set to the outside-air introduction mode, the outside air is introduced into both air passages.
Further, the foot/defroster mode is selected as the air outlet mode, there is set an inside air/outside air double laminar mode in which the inside air is introduced into the first air passage and the outside air is introduced into the second air passage. In this way, because a passenger compartment is heated by a recirculation of the inside air which has been already heated, the heating performance is improved. Further, because the outside air having a low humidity is blown toward the windshield, it is possible to obtain the defrosting performance of the windshield certainly.
When the foot/defroster mode is selected as the air outlet mode, generally, approximately 50% of air is blown out from the foot air outlet, and approximately 50% of air is blown out from the defroster air outlet. Further, when the foot mode is selected as the air outlet mode, generally, approximately 80% of air is blown out from the foot air outlet, and approximately 20% of air is blown out from the defroster air outlet.
Thus, between the foot/defroster mode and the foot mode, a ratio of amounts of the blown-air greatly varies. He inventors of the present invention have experimentally produced an air conditioning apparatus having a function of the above-described inside air/outside air double laminar mode, in which a communication path is formed at an air downstream side of a heating heat exchanger to communicate between the first air passage at a side of the inside air and the second air passage at a side of the outside air, and the ratio of amounts of the blown-air is varied by a variation of an amount of air passing through the communication path.
However, as a result of studies and examinations of the air conditioning apparatus having the communication path, which has been produced experimentally, the inside air in the first air passage is mixed into the outside air in the second air passage so that a defrosting performance of the windshield is deteriorated. As a result, the windshield may be frosted or clouded.